Stroboscopic tuning apparatus



J. H. 'MAYBERRY STROBOSCOPIC TUNING APPARATUS Filed Jan. 5, 1944glu/verdon J. ff. MA1/BERRY www0 Feb. 4, 1947.

Patented Feb. 4, v1947 'UNITEDITSTATES PATENT Vor `s'rltolsoscorrc TUNmGAPPARATUS .lohn H. Mayberry, Corpus Christi,K Tex. Application January5, 1944, Serial No. 517145 (o1. :is-14) 2 Claims.

This .invention `relates to limprovements in stroboscopic tuningapparatus and pertains particularly to apparatus of this characterdesigned for visual tuning. f

In some present known types yof stroboscopes use ismade of gears fordrivingv or turning the rotating members. the use of gears, to drive theusual discs which areemployed each for a particulartone, to ob-A tainspeed ratios between the discs` of thesame value as the ratios between'the numbers of vibrations in the successive chromatic notes. As iscorrectly stated vin prior Patent No. 2,286,030 an exact ratio cannotvbe secured by the use of gears andvarious means have 4been devised forcompensating this ydeficiency but with all such meansr there stillremains, because of the use of the gears as stated in the patentreferred ltopa margin oferror. v

The present invention has for avprimary ob- Jectvthe provision of astroboscopic tuning apparatus designed primarily for tuning musicalinstruments, although it is not limited to such use, wherein the use ofgears is entirely avoided and whereby the ratios between the rotatingvisual elements or indicators are absolutely the same in the successivechromatic tones.

Another object of the invention is to provide an improved stroboscopicapparatusA which makes possible the measuring of frequencies which comeout in fractions. l n

Still another,A object of the invention isto provide an improvedstroboscopic tuning apparatus making use of a single rotating memberwhich carries a plurality ofgroups of symbols representing tone ing adirect ratio to' a known pitch frequency,

as the ratios ybetween the numbers yof vibrations frequency or pitchvalues each havy However it is not possible, by i with a synchronousmotor operating means for turning' the member at a known speed wherebythe correctness of tone of any one of.' the numberr of tones'of lknownpitch value covered by such groups will be shown upon causingtheiiashing frequency of an `illuminating lamp to be varied overtherange of the frequencies `of the tones represented by the said groups.

Still another object of the invention is to `provideran improvedstroboscopic apparatusof the character above set forth in which theseries of values carried Iby the rotating member is graduated to coverthe pitch of tones over an entire octave and in which the member isrotated at synchronousspeed for coaction with a asher controlled byelectric current vibrationshaving frequencies corresponding to soundvibrations.

a conventional manner withV an Another object of the invention is toprovide a stroboscopic apparatus of the characterabove stated, by meansvof which a change `I,in speed will change the'v pitch offthe fentire inwhich, also, it is possibleV to tune several octaves without changingthev 'speed of rotation yof the turning member or by which the pitch maybe raised a.frafzticnfof a` tone `or to a suillcient'vdegree' to placethe entire pattern of the tone value indicating symbols on the Vrotatingmember, in a diierent octave by changingv the synchronous'speed of therotating member.

Many other ladvantages and objects ofy the present invention will becomeapparent as the description of the same proceeds, and the invention will'be best understood from a consideration of the following detaileddescription taken in connection with ,the accompanying' drawing forminga part of the specification, it being -understood that minor changes andmodiiications may be made in the invention so long asvsuch changes andmodifications mark no material de-v parture from the salient features ofthe invention as expressed lin the appended claims.

In the drawing: y d Figure` 1 is a diagrammatic illustration of astroboscopic apparatus constructed'in accordance with the presentinvention.

Figure 2 illustrates conventionally a form of synchronous ymotor forminga part of the cylinder structure. f

Figure 3 is a diagram illustrating the application of the invention to avibrator.

Figure 4 illustrates a form of casing Ior housing in which the apparatusmay be inclosed ior use.

In accordance with the form of a microphone I0, which is coupled inapparatus l l of any conventional design. Y

The out-'put of the amplifier is fed into a neon or gas discharge tubelI2 through an impedance matching transformer. Accordingly as will bereadily recognized the apparatus translates sound vibrations intoelectric current vibrations having corresponding frequency and the glowlamp or tube l2 will be energized by said current vibra-l tions at thesame frequencies as those of the sound vibrations picked up bythemicrophone I0.

The stroboscopic member of the present ap-` octave and the presentinvention, an s illustrative embodiment of whichy is diagram-` maticallyshown inthe accompanying drawing there is-provided a sound pick-upinstrument in audiofamplifying pali'atus is in the form of a cylinder I3which is horizontally disposed and rotatablysupported at-its ends, inany suitable manner for rotation Y.

about its longitudinal axis. The cylinder forms 'ana integral part ofand Ais turned by a synchroto the .pickup and amplifying system asillus-l 'trated.

While there has been shown and described a` lsynchronous motor turningat two and a half revolutions per second, there may be employed a motorturning at any other synchronous speed such as 3.157 R. P.-S., whichconstruction would, Y

. of course, require 38 poles instead of 24 as previously stated for'therst-mentioned speed.

AThe cylinder I3 has formed around the surface' I2 encircling series ofdots, squares or other suit'- able symbols which make up a black andwhite pattern corresponding to l2 tones in a chromatic. octave, theoctave selected for use being that below middle C on a key-boardinstrument.

While itis not essential to the use of the inl t vention that thecylinder be inclosedin a housing, such housing is, however, illustratedand designated I 6, with the slot window I 1 through which may be viewedthe series of circular linesof symbols carried bythe cylinder. TheProvision., of

such a housing also makes convenient the placement of the values I8 eachabove anddesignating the number of dots or symbols in each of thelcircular lines or series,4

' Below the window and in the line with values I8 maybe placed theconventional tone symbols I9 of Athe selected octave with the frequencyvalues thereof as/i'ndicated at 20.

The whole `tones such, for example, as A1220,

will have an even number of dotsor symbols in l C-261.62, are arrangedto spiral around thecyl-v inder insuch a way as to make at least threecomplete rcircles of the cylinder as `indicated at 2 I. The series ofdots above referredto asdesignating the tone A, is designated 22. Y Y

The values indicated at I8 above the window give the number of symbolsin each circular series forming a fraction of the frequencyv values forthe under-lying indicated tones. When the` cylinder is turned by thesynchronous motor at the selected speed and the lamp I2 is flashed atthe correct frequency of a particular tone, such as A, for example, theflashes of the lamp and the movement of the dots each past one pointwillk be synchronized yso that the dots or symbols of the series A willappear to be stationary thereby showing the toneto be at the properpitch or spiral series 2 I, the dots are in such number and arrangementthat in one revolution of the cylinder 104.65 dots will pass the pointof observation and upon turning of the cylinder two and a half measuringof frequencies which come outy in fractions. Since in any key-boardinstrument it is necessary to set a temperament in order to play Yinmany keys without using anv inconveniently large number o keys to theoctave, the temperament, which it vis necessary to set. on theseinstruments determines the degree of departure from the pure scale inorder to accomplish this. This is also the reason why the tones come outin fractions. As previously pointed out the use of gears in a device ofthe character herein described to obtain a separate vpattern for eachtone, is not `possible since the mathematical ratio available with theuse of gears will not give the required separation.

The separation of the tones inany key-board `instrument graduates at theratio of the twelfth root of two, or in other words Aa ratio of 1.05946.This separation cannot be obtained by the use of gears in the rotationof patterns as set forth y above but it is possible for the rotation ofthey patterns by the means herein disclosed.

In further illustration of how the desired sep-l aration orratio betweenthe patterns is obtained to correspond to the separation between thefrequencies of the tones of the chromaticscalathe illustration in Figure1 makes clear how, on a basis of 2.5 revolutions per second for thecylinder the frequencies noted are available, which frequencies coverthe octave below C, universal pitch of A-440. If the cylinder isrevolved at two times this speed, or five revolutions per second, thenext higher octave will be available, begin-` ning with C sharp-277.18.

The observed pattern remains in'tune within of the present invention,the musical tone isiirst Y picked up by the microphone I0 and amplifiedby the audio-amplifier unit II. The output of the amplifier unit is fedinto the tube I2, which may be a neon or any suitable tube, thusilluminating the revolving' pattern. Since the eye cannot separatepulsations of light above 26 per second, the light will appear to besteady.

The pattern is being turned at a denite rate of speed with the black andwhite lines passing the point of observation corresponding to the tonesof the chromatic tempered musical scale. For example, the tone of A-220C. P. S. is sounded and at the same time the A zone of the revolvingpattern is observed. There are 220 black lines per second passing thepoint of observation. If thev tone is in tune, a black line will be atthe same place every time the light flashes, or every 1,220 of a second,therefore, the zone will appear stationary.

I1', for example, the tone was 219 C. P. S., the black lines or dotswould continue to pass at 220 lines per second andthe light would beflashing only 219 times per second. Thus the line, or dot, will appearat a slightly different place each time and will move the interval ofone line per second in the direction of the pattern rotation ormovement. If, however, the tone was 221 C. P. S., the line or dot wouldappear' to recede, or move back, from the direction of pattern rotation.

In the case of fractional tones, such, for vexample, as the tone ofD293.67, the intervalbetween the lines or dotswill allow one line or dotto pass the point of observation every 1/293.67 of a second. Since inany stroboscopic apparatus resonance is denoted by the apparentstability of the zone, the interval between all lines or dots on thecomponent or zone of the pattern must be the same, just as the timeinterval between flashes of light must be the same for the particularfrequency under observation. Spiral components or zones were designedfor the tones of fractional frequency with the correct interval betweenlines or dots corresponding to the tone of fractional frequency. Inobserving the pattern i-t is not necessary to follow one turn of thespiral, but to observe all of the zone as a whole since all ofthe linesor dots of the zone are equally spaced. Resonance is denoted in theusual manner, that is, by the apparent stability of the zone.

The 412 semitones or half-tones of the octave of the chromatic temperedscale are therefore designed for the ratio of the 12th root of 2 or agraduation of 1.05946 per semitone, the single pattern with 12 zones orcomponents of the pattern corresponding to the frequency of the tones ofthe standard octave when tempered.

The pitch could be changed, however, changing the speed of rotation.-

Figure 3 illustrates a method of tuning a vibrator with the use of anignition coil 24, the vibrator being designated 23. The neon tube isconnected across the secondary of the ignition coil while the primary ofthe coilA is connected across the vibrator points for excitation. Aresistance 25 of twenty thousand ohms is placed in series with thesecondary of the coil and the neon or gas discharge tube. to avoidover-load.

The present device is selective and discriminates between noise and amusical tone. It is possible for one to teli at a glance whether a toneis sharp or at. If the tone is in tune or in resonance the pattern willremain stationary but it it is sharp the `dots will move upward, and ifit is ilat the dots will move downward. When the `tone is adjusted sothat the pattern remains stationary, the tone will be in resonance or inunison with the revolving pattern.

The technique ofthe instrument is mechanically perfect since the patternremains ilxed and the established ratio of vibration for each tone isxed. Operation of the device at a higher or lower speed will change thepitch of the entire octave but at the same time alltones within therotating pattern bear a linear relationship between each other. If thespeed is doubled, for instance, the octave higher can be tuned aspreviously pointed out.

It is also possible to tune several octaves without changing the speed,however the patterns will appear diferently. For example the octaveabove will make the dots appear to be twice in number and there willalso be a shift in the position. The octave below will look much, likethe fundamental octave but not so sharp. An instrument can b tuned toany pitch by changing the to thus eliminatethe use of governors orvarious means of imparting the desired speed to the cylinder. K

The -pitch may be raised a fraction of a tone or it may be raised enoughto place the entire pattern in a different octave. For example, turningthe cylinder at 3.157 revolutions per second which is a synchronousspeed, will give the octave F to E around middle C in the pitchorali-441.1. It will be noted that the even number of dotspreviouslyused for F sharp, as illustrated in Figure 1 now becomes Asharp-233.70 which is a fraction. 'I'his is an example of theflexibility of the apparatus. Any desired pitch can be obtained bychanging the speed of rotation oi' the cylinder.

Two tones can also .be sounded simultaneously and the respectivepatterns will be observed on the device at the same time, since thefrequencies will be different and the observer may easily note twosymbol groups simultaneously, each of which would represent a tone andbe illuminated at the tone frequency.

While in the preceding description reference has been made entirely tothe tuning of musical instruments it is to be understood that lthere isno intention of limiting the scope of the invention to such use since itmay be used to-tune any piece of apparatus producing an audible soundsuch as mechanical vibrators and automobile horns, or for measuring thespeed of rotating objects, calibrating oscillators, and checkingtachometers.

I claim:

1. A stroboscopic apparatus, comprising a body supported for rotation, anumber of groups of symbols carried by such body, the symbols o! eachgroup being disposed around and substantially concentric with the axisof rotation of the body, each group representing a tone of the musicalscale, the symbols representing the tones of even frequency beingarranged in a circle and the symbols representing tones oi' fractionalfrequency being arranged to form a spiral, each of said groupsconsisting of a whole number of identical symbols, the symbols of eachgroup being equally spaced apart so that the same number of symbolspasses a point of observation with each revolution of the body, meansfor turning the body on said axis at an unvarying number oi' revolutionsper second, which number of revo'- lutions multiplied by the number ofsymbols passing the point of observation per revolution is the exactfrequency `of the musical tone represented .by each group of symbols,means for translating sound vibrations into electric current vibrationshaving corresponding frequencies, and a glow lamp arranged to illuminatethe body and the groups of symbols and connected with the soundtranslating means to be energized by the electric current vibrations atthe said frequencies.

2. A stroboscopic apparatus, comprising a body supported for rotation, agroup of symbols on said body and arranged around and substantiallyconcentric with the axis of rotation of the body, the group consistingof a whole number of identical symbols, said group representing amusical tone of fractional frequency and lbeing arranged in a spiral,the symbols of the group being equally spaced apart, so that the samenu'mber of symbols passes a point of observation with each revolution ofthe body, means for turning the body on said axis at an unvarying numberof revolutions per second, which number of revolutions multiplied by thenumber of symbols passing the point of observation per revolution is theexact frequency of the musical tone represented by the group, means fortranslating sound vibrations into electric current vibrations havingcorre- 5 sponding frequencies, and a glow lamp arranged to illuminatethe body and groups of symbols and connected with the sound translatingmeans to be energized by the electric currentl vibrations at the saidfrequencies,

JOHN H. MAYBERRY.

REFERENCES CITED `Ihe following references are of record in the le ofthis patent:

Number UNITED STATES PATENTS Name Date Kriek June 7, 1938l Young et a1June 9, 1942 Elton Sept. 22l 1942 Dodd Nov. 25, 1919

